The mission of the OSUCCC Proteomics Shared Resource (PSR) is to provide instrumentation, scientific expertise and shared research services for the identification of proteins, protein modifications and protein biomarkers to advance the productivity of cancer research of OSUCCC members at cost effective rates. High-quality proteomic analysis requires sophisticated protein separation approaches, image analysis capabilities, a variety of mass spectrometric systems, and advanced bioinformatics capabilities. The PSR is designed to provide affordable and high-quality service in each of these areas. Experienced PSR staff members provide effective services to identify proteins or protein complexes using the current state-of-theart mass spectrometers and supporting equipment Outstanding institutional support and value-added partnerships allow the PSR to offer a complete range of equipment and expertise for ID PAGE, 2D PAGE, multiplex analysis and differential image gel electrophoresis (DIGE), protein complex and post-translational modification analysis and other experimental approaches requiring protein identification. These services are linked to other key OSUCCC Shared Resources such as the Biomedical Informatics Shared Resource as well as PSR-supported bioinformatic tools required for data mining, including Mascot on a 16-node cluster. Kari Green-Church, Ph.D., and a team of highly-trained staff provide established scientific leadership for PSR to give OSUCCC cancer investigators effective technical expertise for proteomic analysis. Consultative services guide OSUCCC researchers seeking to address research questions from chemical and protein biomarker determination to unraveling complex protein-protein interactions from basic science experiments. Since 2004, over $4.0 million of institutional support has been invested in the operation and expansion of the PSR, providing staff salaries and cost matches for new instrumentation User fees generated are effectively leveraged for the operation costs (maintenance agreements, supplies and upgrades). The PSR has shown increased usage by OSUCCC members, now exceeding 48 members representing five of six OSUCCC Scientific Programs. OSUCCC members account for more than 56% of total usage of the PSR. This is a solid increase from 2004 when approximately 30 OSUCCC members used the shared resource and only constituted less than 30% of total usage. Collectively, PSR supports a wide range of services from standard proteomic assays to innovative consultative expertise to enhance cancer-relevant studies. It offers cancer investigators the critical tools and expertise needed for identifying proteins, quantifying protein expression levels, discovery of protein modifications and protein biomarkers We now request CCSG funding forthe PSR that will provide 19.4% of the total support for this important full Shared Resource over the next five years.